Final answer:
Prince Henry the Navigator was the Portuguese prince who led the encouragement of European exploration. He started the navigational school and sponsored the exploration of the African coast. Pedro Cabral was the first to claim Brazil for Portugal.
Step-by-step explanation:
The chief leader in encouraging European exploration was Prince Henry the Navigator. He was not only instrumental in initiating Portugal's voyages of discovery but also established a school for navigational studies. The Portuguese, under his sponsorship, began exploring the coast of Africa with the motivations of trade and spreading Christianity. Through his support, Portugal secured a leading position in the European Age of Discovery, paving the way for other explorations like the journey to India and the establishment of a sea empire.
Regarding the first explorer to reach Brazil and claim it for the throne of Portugal, the answer is Pedro Cabral. Cabral's arrival in Brazil in the year 1500 extended Portugal's influence into the South American continent.